The invention relates to the field of robotics and more specific to manipulators used for the remote handling of objects.
As such telemanipulation control systems are known. Several embodiments are described in "Developments of new force reflecting control schemes and an application to a teleoperation training simulator" by Won S. Kim in Proceedings of the 1992 IEEE International Conference on Robotics and Automation, May 1992. In this article several classes of systems are distinguished.
In a first class of prior art controllers, the so-called force reflecting (FR) controllers, the position of the remote manipulator (slave) is controlled by a human operator through a master arm, while the contact forces in the slave are sensed by a force sensor and are reflected back to the master arm. Due to stability problems the force reflection gain is limited to approximately 1/10, i.e. when the remote manipulator arms senses 10 N the operator can only sense 1 N.
A second class of prior art controllers is based on the so-called shared compliance control (SCC). This type of control makes the robot more compliant by low pass filtering the force from the sensor. In this way the force reflection gain can be increased.
A third class of prior art controllers uses a combination of FR and SCC.
A fourth class of prior art controllers uses the position error based force reflection, where the force reflection is made proportional to the position error between the commanded and actual position of the slave arm.
The fifth class of prior art controllers is a combination of SCC and position error based force reflection.
A common characteristic of all the above-described prior art controllers is that these controllers use the commanded position of the human operator (the manual controller) as a commanded position (setpoint position) for the remote arm. All the prior art controllers are therefore essentially position controllers, dependent on the control (and therefore the existence) of a position error between the commanded position (human operator) and the actual position of the remote manipulator arm. Dependent on the class of prior art controllers this position error is noticeable (for example feels as a damped spring) between hand controller and remote controller and does not allow accurate positioning and "feel" due to this compliance.
U.S. Pat. No. 5,116,180 describes a telemanipulation system where only the force from the remote manipulator arm is sensed and fed back to the hand controller.
The international patent application WO-9510080 describes a system where a force is calculated based on position only.
U.S. Pat. No. 5,004,391 describes a system where only the force from the remote manipulator arm is sensed and fed back to the hand controller.
The article "A new Robot for High Dexterity Microsurgery" by P. S. Schenker et al., Proceedings of the first International Conference of CVRMed'95, April 1995, describes a system based on position control only.